Regulator for dynamo-electric machines



(N m a 1. B o e s. D. FIELD. ESTAVA'LABLE P REGULATOR FOR DYNAMO BLBGTRIG MACHINES.

No. 391,954. Patented ott. 30, 1888.

ATTORNEYS.

WITNESSES mi: (Mmk u,

BEST AVAILABLE COP PATENT OFFICE.

STEPHEN DUDLEY FIELD, OF YONKERS, NEXV YORK.

REGULATOR FOR DYNAMO-ELECTRIC MACHINES.

SPECIFICATION forming part of'Letters Patent 110391.954, dated October 30, 1888.

A mplication filed October ll, 1887. Serial No.259,986. (No model.)

To all whom 2115 may concern.-

Be it known that I, STEPHEN D UDLEY FIELD, a citizen of the United States, and a resident of Yonkers, in the State of New York, have invented certain new and useful Improvements in Dynamo-Electric Machines and Electric Motors, of which the following is a specification.

In every dynamo or electric motor there will be found a certain position for the brushes where the spark is least or entirely absent; but any departure from such position will cause more or less sparking and consequent wear of both brushes and commutator. On the other hand, when the brushes are normally in sparklessposition and the electrical output fromthe dynamo or the electrical energy absorbed by the motor is subject to sudden and considerable changes, the position of least or no spark changes accordingly, and unless the brushes are moved to compensate for the change they and the commutator will suffer in proportion.

The object of the present invention is to provide a sensitive automatic visual indicator which will at all times show whether the brushes are at the position of least spark or away from it, and, if the latter, will show the direction of movement required to restore them and the distance to be moved.

'Theinvention is more particularly intended for application to electric locomotives and cars, where an attendant is always present and will have the indicator constantly in view and the adj usting-lever under his hand ready for instant manipulation in response to the conditions of actual performance.

To this and other ends accordingly my invention consists in the arrangement of circuits and combination and construction of devices, substantially as hereinafter more fully described and claimed.

In the drawings herewith, Figure 1 is an end view of an electric motor, which in this instance is shown with the armature and fieldmagnets in series and an adjustable liquid rheostat in the circuit, the figure also showing the reversii'ig-lever as combined with brushshifting devices and visual indicator with its peculiar arrangement of circuits. Fig. 2 is a perspective of the commutator as constructed in practice. Fig. 3 is a detail showing the addition of an audible alarm.

In all dynamos and motors whose armature is a closed circuit touched at two points by collecting-brushes, a point can be found on the comnifitator which equally divides the rise of potential if a dynamo, and the fall of potential it a motor, between'the positive and negative brushes. Whether this point is midway between the brushes depends on various circumstances-such asthe relative strength of magnetism between the field and armatu re core, the character of distribution of the lines of force, and the amount of distortion, &c.

A is the field-magnet circuit; B B, the main brushes; C, the commutator, and D the armature, the front bearing being removed for the sake of clear-mess. The brushes B B are carried by a ring, E, (but insulated therefrom,) which is freely rotatablebetween the frictionwheels 9, set on the poles N and S of the motor. Wheels 9 are made of or covered with an insulating material or otherwise insulated. RingE is grooved peripherally, and should be covered with an insulating material.

From two fixed points, h it, through the tension-springs i i, I pass two flexible wire cables, k k, which respectively pass down under the upper friction wheels around the grooved periphery of the ring E till they reach the lower wheels, 9, whence they pass up to the respective ends of the pivoted reversinglever K, whose ends are insulated from each other. The cables is k are electrically connected to their respective springs i i and to their re spective brushes B B, and their friction on the ring E is sufiicient to rotate it when they are moved by the lever K. One side of the main or supply circuit leads to the two contacts I l of the switch, and the other two contacts, in m, of the switch are connected through the rheostat R and the field-magnets A to the other side of the supply-circuit.

The lever K is made so that in either of its positions it has a considerable range of movement to impart to the brushes B B without breaking or reversing the circuit through the armature.

The arrangement of the visual indicator is as follows: Having found the point on the commutator which bisects the fall of potential, I mark it for the location of the extra brush B As this will be always at a position of strong induction, I prefer to take current only from every second or third bar. For lhispurpose every second or third bar of the commutator G is fitted with a metal pin, 0, or other projection from its end. The extra brush B is carried by the ring E, and is insulated therefrom. The brush is made in the form of a spring-wiper and standsin the line of travel of the pins 0, so as to make contact with them successively but one at a time.

I construct a bobbin, 1?, with closed bottom and wind it with two high-resistance coils, t t. Coil tis included in the circuit between extra brush B and brush 13, while coil t is in eluded in the circuit between extra brush 13 and brush B. Coils t t are balanced as to magnetic effect and resistance, but are connected difl'erentially, so as to neutralize each other when the currents flowing through them are equal. In the cup of the bobbin I mount a magnetized needle, u,-(prefer'ably in theform of ahollow cylinder,) pivoted in bearings o and provided with pointer w, extending upwardly, as shown. The bobbirrcup is then filled with oil to decrease the gravity of the needle and lubricate its bearings. The coilst t are of so high a resistance that the additional current in the corresponding portions of the armature will be too trifling to disturb the magnetic equilibrium subsisting between the armature and field magnetism.

As long as the two currentsin coils ti are e'iia'ctly equalthe pointer w will stand verti- 03.1; but the slightest excess in either coil due to a preponderating fall of potential between its terminals arising from a change of density in the lines of force at its corresponding portion of the armature will instantly deflect the pointer w to one side or the other. The polarities are so arranged that the pointer will move'in the direction in which the brushes B B are'displaced. This at once not only indicates' the fact that brushes B B need adjustment, but shows the direction in which they should be moved to restore them to sparkless position. A scale, m, is placed behind the pointer, and is preferably calibrated and marked to indicate in small fractions of an inch or meter the amount of displacement, or

. the are of movement to be given the adjusting-lever to restore the brushes B B to their proper position.

The operation of moving the brushes is purely manual. The attendant watches the pointer, and the instant it varies from zero he moves his brush-lever in the required direc tion and to the precise extent needed to restore the brushes to the zero or non-sparking position. I have described a particular arrangement of devices for this purpose; but ob viously a great variety of arrangements are open to the selection of the builder. I therefore do not confine the scope of this invention BEST AVAILABLE cop to any particular form or construction of parts. As stated, the invention is applicable to both motors and generators wherever used. Evidently when two or more motors are used in electri crailway service, each could h ave its own pole-changing switch and indicating-galvanometer. It may be well to state also that so sensitive can this arrangement be made thata displacement of the brushes of one hundredth ofan inch can be easily discerned and corrected.

Obviously the galvanometer may be utilized also to produce an audible alarm, if desired. In Fig. 3 the metallic pointer w will, on a deflection of, say, one-sixteenth of an inch in either direction, lightly touch contacts 1 2 and close the circuit of a vibrating bell, 3 In the ap plication of my invention to generators at snpplystations this audible alarm may be of considerable importance, and where several machines are in use the bell of each may easily be given a distinguishing tone.

I claim as my invention 1. In a dynamo-electric machine or electric motor, the combination, with the armature, of a differential galvanometer whose respectiv'e'coils are differentially included in two circuits derived from portions of the armature circuit selected to normally balance each other in electric energy only when the brushes are at the position of least spark, substantially as described,whereby displacement of thebrushes from such position is visually made known.

2. In a dynamo-electric machine or electric motor, the combination, with the armature, of a differential galvanometer whose respect ive coils are differentiallyincluded in two circuits derived from portions of the armaturecircuit selected to normally balance each'other in electric energy only when the brushes are at the position of least spark, and a pointer and scale for such galvanometer adapted to'indicate the direction of displacement of brushes from their normal position, substantially as described.

8. In a dynamoelectric machine or electric motor, the combination, with the armature, of a differential galvanometer whose respective coils are differentially included in two circuits derived from the main brushes, and one or two supplementary brushes, and adapted to visually indicate abnormal conditions of the potential in said circuit, substantially as described.

4. In a dynamo-electric machine or electric motor, the combination, with the armature, of a difierential galvanometer included in two circuits derived from portions of the armature normally balancing each other when the pointer of a galvanometer is at zero, and an alarm-circuit including an audible alarm, a source of current, and contacts for the alarmeircuit adapted to be closed by the pointer when it departs from its zero position, substantially as described.

5. In a dynamo-electric machine or electric motor, the combination of the armature, the

391.954 AILABLE COP brushes, a movable holder therefor, a polewhereby the brushes may be adjusted in either changing switch mechanically connected to position by the switch-lever without prcvent- [0 said brush-holder and having a range of ading the operation of the indicating device. justin motion in each direction and an elec- T 5 trical indicating device connected by one ter- SDEPHEN DUD LE1 FIELD minal with one. or both said brushes, and by Vitnesses: the other terminal with an intermediate point I \V. L. CANDEE, of the commutator, substantiall y as described, T. J. MOTIGHE. 

